Refactor, into a common function, the version and capability negotiation
done when invoking a long-running process as a clean or smudge filter.
This will be useful for other Git code that needs to interact similarly
with a long-running process.
As you can see in the change to t0021, this commit changes the error
message reported when the long-running process does not introduce itself
with the expected "server"-terminated line. Originally, the error
message reports that the filter "does not support filter protocol
version 2", differentiating between the old single-file filter protocol
and the new multi-file filter protocol - I have updated it to something
more generic and useful.
Signed-off-by: Jonathan Tan <jonathantanmy@xxxxxxxxxx>
---
convert.c | 75 ++++--------------------------------
pkt-line.c | 19 ----------
pkt-line.h | 2 -
sub-process.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++
sub-process.h | 26 +++++++++++++
t/t0021-conversion.sh | 2 +-
6 files changed, 137 insertions(+), 90 deletions(-)
diff --git a/convert.c b/convert.c
index dbdbb24e4..1012462e3 100644
--- a/convert.c
+++ b/convert.c
@@ -513,78 +513,17 @@ static struct hashmap subprocess_map;
static int start_multi_file_filter_fn(struct subprocess_entry *subprocess)
{
- int err, i;
- struct cmd2process *entry = (struct cmd2process *)subprocess;
- struct string_list cap_list = STRING_LIST_INIT_NODUP;
- char *cap_buf;
- const char *cap_name;
- struct child_process *process = &subprocess->process;
- const char *cmd = subprocess->cmd;
-
- static const struct {
- const char *name;
- unsigned int cap;
- } known_caps[] = {
+ static int versions[] = {2, 0};
+ static struct subprocess_capability capabilities[] = {
{ "clean", CAP_CLEAN },
{ "smudge", CAP_SMUDGE },
{ "delay", CAP_DELAY },
+ { NULL, 0 }
};
-
- sigchain_push(SIGPIPE, SIG_IGN);
-
- err = packet_writel(process->in, "git-filter-client", "version=2", NULL);
- if (err)
- goto done;
-
- err = strcmp(packet_read_line(process->out, NULL), "git-filter-server");
- if (err) {
- error("external filter '%s' does not support filter protocol version 2", cmd);
- goto done;
- }
- err = strcmp(packet_read_line(process->out, NULL), "version=2");
- if (err)
- goto done;
- err = packet_read_line(process->out, NULL) != NULL;
- if (err)
- goto done;
-
- for (i = 0; i < ARRAY_SIZE(known_caps); ++i) {
- err = packet_write_fmt_gently(
- process->in, "capability=%s\n", known_caps[i].name);
- if (err)
- goto done;
- }
- err = packet_flush_gently(process->in);
- if (err)
- goto done;
-
- for (;;) {
- cap_buf = packet_read_line(process->out, NULL);
- if (!cap_buf)
- break;
- string_list_split_in_place(&cap_list, cap_buf, '=', 1);
-
- if (cap_list.nr != 2 || strcmp(cap_list.items[0].string, "capability"))
- continue;
-
- cap_name = cap_list.items[1].string;
- i = ARRAY_SIZE(known_caps) - 1;
- while (i >= 0 && strcmp(cap_name, known_caps[i].name))
- i--;
-
- if (i >= 0)
- entry->supported_capabilities |= known_caps[i].cap;
- else
- warning("external filter '%s' requested unsupported filter capability '%s'",
- cmd, cap_name);
-
- string_list_clear(&cap_list, 0);
- }
-
-done:
- sigchain_pop(SIGPIPE);
-
- return err;
+ struct cmd2process *entry = (struct cmd2process *)subprocess;
+ return subprocess_handshake(subprocess, "git-filter", versions, NULL,
+ capabilities,
+ &entry->supported_capabilities);
}
static void handle_filter_error(const struct strbuf *filter_status,
diff --git a/pkt-line.c b/pkt-line.c
index 9d845ecc3..7db911957 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -171,25 +171,6 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
return status;
}
-int packet_writel(int fd, const char *line, ...)
-{
- va_list args;
- int err;
- va_start(args, line);
- for (;;) {
- if (!line)
- break;
- if (strlen(line) > LARGE_PACKET_DATA_MAX)
- return -1;
- err = packet_write_fmt_gently(fd, "%s\n", line);
- if (err)
- return err;
- line = va_arg(args, const char*);
- }
- va_end(args);
- return packet_flush_gently(fd);
-}
-
static int packet_write_gently(const int fd_out, const char *buf, size_t size)
{
static char packet_write_buffer[LARGE_PACKET_MAX];
diff --git a/pkt-line.h b/pkt-line.h
index 450183b64..66ef610fc 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -25,8 +25,6 @@ void packet_buf_flush(struct strbuf *buf);
void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
int packet_flush_gently(int fd);
int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
-LAST_ARG_MUST_BE_NULL
-int packet_writel(int fd, const char *line, ...);
int write_packetized_from_fd(int fd_in, int fd_out);
int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
diff --git a/sub-process.c b/sub-process.c
index 6cbffa440..37b4bd0ad 100644
--- a/sub-process.c
+++ b/sub-process.c
@@ -108,3 +108,106 @@ int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, co
hashmap_add(hashmap, entry);
return 0;
}
+
+static int handshake_version(struct child_process *process,
+ const char *welcome_prefix, int *versions,
+ int *chosen_version)
+{
+ int version_scratch;
+ int i;
+ char *line;
+ const char *p;
+
+ if (!chosen_version)
+ chosen_version = &version_scratch;
+
+ if (packet_write_fmt_gently(process->in, "%s-client\n",
+ welcome_prefix))
+ return error("Could not write client identification");
+ for (i = 0; versions[i]; i++) {
+ if (packet_write_fmt_gently(process->in, "version=%d\n",
+ versions[i]))
+ return error("Could not write requested version");
+ }
+ if (packet_flush_gently(process->in))
+ return error("Could not write flush packet");
+
+ if (!(line = packet_read_line(process->out, NULL)) ||
+ !skip_prefix(line, welcome_prefix, &p) ||
+ strcmp(p, "-server"))
+ return error("Unexpected line '%s', expected %s-server",
+ line ? line : "<flush packet>", welcome_prefix);
+ if (!(line = packet_read_line(process->out, NULL)) ||
+ !skip_prefix(line, "version=", &p) ||
+ strtol_i(p, 10, chosen_version))
+ return error("Unexpected line '%s', expected version",
+ line ? line : "<flush packet>");
+ if ((line = packet_read_line(process->out, NULL)))
+ return error("Unexpected line '%s', expected flush", line);
+
+ /* Check to make sure that the version received is supported */
+ for (i = 0; versions[i]; i++) {
+ if (versions[i] == *chosen_version)
+ break;
+ }
+ if (!versions[i])
+ return error("Version %d not supported", *chosen_version);
+
+ return 0;
+}
+
+static int handshake_capabilities(struct child_process *process,
+ struct subprocess_capability *capabilities,
+ unsigned int *supported_capabilities)
+{
+ int i;
+ char *line;
+
+ for (i = 0; capabilities[i].name; i++) {
+ if (packet_write_fmt_gently(process->in, "capability=%s\n",
+ capabilities[i].name))
+ return error("Could not write requested capability");
+ }
+ if (packet_flush_gently(process->in))
+ return error("Could not write flush packet");
+
+ while ((line = packet_read_line(process->out, NULL))) {
+ const char *p;
+ if (!skip_prefix(line, "capability=", &p))
+ continue;
+
+ for (i = 0;
+ capabilities[i].name && strcmp(p, capabilities[i].name);
+ i++)
+ ;
+ if (capabilities[i].name) {
+ if (supported_capabilities)
+ *supported_capabilities |= capabilities[i].flag;
+ } else {
+ warning("external filter requested unsupported filter capability '%s'",
+ p);
+ }
+ }
+
+ return 0;
+}
+
+int subprocess_handshake(struct subprocess_entry *entry,
+ const char *welcome_prefix,
+ int *versions,
+ int *chosen_version,
+ struct subprocess_capability *capabilities,
+ unsigned int *supported_capabilities) {
+ int retval;
+ struct child_process *process = &entry->process;
+
+ sigchain_push(SIGPIPE, SIG_IGN);
+
+ retval = handshake_version(process, welcome_prefix, versions,
+ chosen_version) ||
+ handshake_capabilities(process, capabilities,
+ supported_capabilities);
+
+ sigchain_pop(SIGPIPE);
+ return retval;
+}
diff --git a/sub-process.h b/sub-process.h
index d37c1499a..6857eb1b5 100644
--- a/sub-process.h
+++ b/sub-process.h
@@ -29,6 +29,16 @@ struct subprocess_entry {
struct child_process process;
};
+struct subprocess_capability {
+ const char *name;
+
+ /*
+ * subprocess_handshake will "|=" this value to supported_capabilities
+ * if the server reports that it supports this capability.
+ */
+ unsigned int flag;
+};
+
/* subprocess functions */
/* Function to test two subprocess hashmap entries for equality. */
@@ -62,6 +72,22 @@ static inline struct child_process *subprocess_get_child_process(
return &entry->process;
}
+/*
+ * Perform the version and capability negotiation as described in the "Long
+ * Running Filter Process" section of the gitattributes documentation using the
+ * given requested versions and capabilities. The "versions" and "capabilities"
+ * parameters are arrays terminated by a 0 or blank struct.
+ *
+ * This function is typically called when a subprocess is started (as part of
+ * the "startfn" passed to subprocess_start).
+ */
+int subprocess_handshake(struct subprocess_entry *entry,
+ const char *welcome_prefix,
+ int *versions,
+ int *chosen_version,
+ struct subprocess_capability *capabilities,
+ unsigned int *supported_capabilities);
+
/*
* Helper function that will read packets looking for "status=<foo>"
* key/value pairs and return the value from the last "status" packet
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index eb3d83744..46f8e583c 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -697,7 +697,7 @@ test_expect_success PERL 'invalid process filter must fail (and not hang!)' '
cp "$TEST_ROOT/test.o" test.r &&
test_must_fail git add . 2>git-stderr.log &&
- grep "does not support filter protocol version" git-stderr.log
+ grep "expected git-filter-server" git-stderr.log
)
'
--
2.14.0.rc0.400.g1c36432dff-goog
